The present invention is directed to a small aperture broadband localizing system. A wide variety of attempts exist in the prior art to solve the challenging problem of localizing a broadband or ultra-wideband transmitter so as to enable a real-time location system.
Some attempts rely on a complicated transponder ranging tag that receives and replies to an interrogating signal allowing a receiver to measure two-way time-of-flight, and thus the range to the tag. Transponder tags require complicated, expensive, and power-hungry integrated receivers, thus precluding this as a viable approach to a low-cost, ubiquitous tag.
Other attempts rely on a transmit-only tag and a network of receivers comparing the differential time-of-arrival (DTOA) of transmitted signals from the tag. This architecture allows for a relatively simple and low-cost tag, but requires a complicated and difficult to receive synchronization within a network of receivers.
Still other attempts have involved a relatively large aperture of two or more receive antennas. Such large-aperture angle-of-arrival techniques yield large and bulky receivers that are not terribly practical in the close confines of most typical indoor propagation environments.
There is a need for a simple, compact, and straightforward system to enable a real-time location system by ascertaining angle-of-arrival of broadband and ultra-wideband (UWB) electromagnetic signals.
There is a further need for a simple, compact, and straightforward system to supplement other real-time location architectures by providing angle-of-arrival of broadband and UWB electromagnetic signals.
There is yet additional need for simple, compact, transmit tag antennas that enable compact, robust, body-mounted transmit tags in a real-time location system.